Our implicit assumption has been that since T10 abandoned SRP 2 that the T10/SRP community had little interest in SRP enhancements. If there is IB/SRP community interest we would certainly persue a T10 project of some sort. If StorageGear is the only interested party, then not so much.
Our general target is small clusters that benefit from SSDs. An SSD takes advantage of IB much more fully than an IB RAID box does. Since we support up to 4 hca's, we envision up to 8 system clusters that use our system without needing an IB switch. Enabling low cost switchless clusters doesn't sell many switches directly but enabling low cost IB does help the IB market in general. We think these clusters will want to do random "small" i/o's and that "small" will almost always be larger than 512 bytes. Yes we use giant IUs to be able to hold at least one block. "giant" is relative though. Using srp_sg_tablesize=255 results in an IU of 4148 bytes which is plenty to hold one 4096 byte block. Since our motherboard supports up to 64GB, the overhead of the large IU's is a non-issue for us. Of course the client only transmits the used portion of the IU so non-iu-data-writes remain small on the wire. The client side code simply uses an additional s/g entry passed to the IB layer so no client side copy is done. Ken -----Original Message----- From: Roland Dreier [mailto:[EMAIL PROTECTED] Sent: Monday, July 30, 2007 4:38 PM To: Ken Jeffries Cc: [email protected] Subject: Re: [ofa-general] OFED SRP Client / StorageGear Target / Performance with Modified Write Protocol > We have been doing a fair amount of performance testing on our SRP target. > One thing we found early on was that client writes were considerably slower > than client reads. We addressed this by patching the SRP client code so > that it could include the client write data in the SRP CMD IU if it would > fit. This notion is in iSER but is not in standard SRP. Architecturally, > the capability is signaled using an additional data buffer format bit. > We find that client write performance is considerably improved by using > this capability. We are calling SRP spec compliant writes "standard > writes" and our modified writes "iu data writes". I think this may make sense but you probably want to involve T10 to get it standardized somehow. Also, although I know having a big IOP number is important for various non-technical reasons, are there any realistic storage workloads that do lots of single-block writes? Also I guess you need to use giant IUs to be able to hold at least one block in the IU? - R. _______________________________________________ general mailing list [email protected] http://lists.openfabrics.org/cgi-bin/mailman/listinfo/general To unsubscribe, please visit http://openib.org/mailman/listinfo/openib-general
